<!DOCTYPE html>
<html>
	<head>
		<meta charset="utf-8">
		<title>CSS选择器(重点)</title>
		<style>
			div{
				font-size: 30px;
				color: red;
				text-align: center;
			}
			.Haaaaa{
				font-size: 50px;
				color: black;
				text-align: center;
			}
			#firstDiv{
				color: blue;
				font-size: 20px;
			}
			#secondDiv{
				color: blue;
				font-size: 20px;
			}
		</style>
	</head>
	<body>
		<h2>标记选择器</h2>
		<div>
			吉林很冷
		</div>
		<div>
			所以下雪了
		</div>
		<h2>2.class选择器</h2>
		<div class="Haaaaa">
			1 * 1 = 1
			<span class="Haaaaa">正确</span>
		</div>
		<h3>3.id选择器</h3>
		<div id="firstDiv">嗯哼</div>
		<div id="secondDiv">啊哈</div>
	</body>
</html>